Field of the Invention
The present invention generally relates to the field of ophthalmology. More specifically, the present invention relates to a system for smoothing an irregular surface of a cornea during an opthalmological surgery, such as a femto refractive surgery.
Description of the Related Art
Femto refractive surgery has become fairly common in recent years for its high accuracy and low risk approaches. Over the past decades, the systems along with the operation procedures have been significantly improved to maximize the efficacy and minimize the side effects of this type of surgeries.
For example, Kuehnert et al. in U.S. Pat. No. 8,491,575 B2 describes a laser system and the correcting apparatus for generating a correcting cut surface in the cornea of an eye to correct ametropia. The system comprises a laser unit to emit pulsed laser radiation, a control unit for control of the laser unit, as well as a contact element releasably coupled to the laser unit and specifically adapted for the respective correcting cut surface. The pulse duration is, for example, within the femtosecond range (e.g. 50 to 800 fs), with a pulse repetition rate of between 10 and 500 kHz.
The pulsed laser radiation is focused through the contact element into the cornea of an eye. Focusing is effected by two deflecting mirrors that form a movable scanner and by the optics. Scanning occurs under the control of the control unit, so that basically any desired locations in the cornea can be exposed to the pulsed laser radiation. The control unit controls the laser unit such that an optical breakthrough is generated at the respective focus position in the cornea to separate tissue. The focus positions are selected to be adjacent to each other such that a desired cut surface is present in the cornea.
The laser unit and control unit disclosed in U.S. Pat. No. 8,491,575 can be utilized, for example, in the same manner as in a conventional laser keratome, such as used in the so-called LASIK method (laser in situ keratomileusis) to cut a thin lamella (often referred to also as flap) which is unilaterally detached from the cornea. Thus, the optics, merely represented as a lens, can comprise several optical elements are suitably arranged along the beam path from the laser up to the contact element. For example, the apparatus may further comprise at least a third contact element, which imposes a further curvature upon the anterior corneal surface when contacting the latter, the further curvature deviating from the standard curvature as well as from the actual curvature of the second contact element, and thus has the effect that a cut surface generated using the standard setting results in a further correcting cut surface.
Moreover, the contact surface of the corresponding contact element defining the actual curvature may be flexible. The flexibility is selected such that minor irregularities can be compensated for although on average the actual curvature is imposed upon the anterior corneal surface. This has the advantageous effect that the correcting cut surface to be generated has an extremely smooth profile. However, while the flexibility may be achieved, for example, by a thin, flexible layer, e.g. a gel layer, forming the contact surface, which is in turn applied to a contact element carrier that is rigid with respect to the cornea, the flexible layer disclosed in U.S. Pat. No. 8,491,575 is pre-molded and has limited ability to deform in situ to fit into the corneal surface irregularities.
Therefore, there is a recognized need in the art for an opthalmological surgical system and method that comprises a gel layer that fills the irregularities on the anterior surface of a cornea. Particularly, the prior art is deficient in an opthalmologically useful gel to smooth the irregularities in a femto refractive surgery. The present invention fulfills this long-standing need and desire in the art.